{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2021-47607",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2021-47607",
    "idYear": 2021,
    "status": "PUBLISHED",
    "publishedAt": "2024-06-19T14:54:05.700Z",
    "updatedAt": "2026-05-11T13:57:48.965Z",
    "importedAt": "2026-10-24T01:56:36.661Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "bpf: Fix kernel address leakage in atomic cmpxchg's r0 aux reg",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix kernel address leakage in atomic cmpxchg's r0 aux reg\n\nThe implementation of BPF_CMPXCHG on a high level has the following parameters:\n\n  .-[old-val]                                          .-[new-val]\n  BPF_R0 = cmpxchg{32,64}(DST_REG + insn->off, BPF_R0, SRC_REG)\n                          `-[mem-loc]          `-[old-val]\n\nGiven a BPF insn can only have two registers (dst, src), the R0 is fixed and\nused as an auxilliary register for input (old value) as well as output (returning\nold value from memory location). While the verifier performs a number of safety\nchecks, it misses to reject unprivileged programs where R0 contains a pointer as\nold value.\n\nThrough brute-forcing it takes about ~16sec on my machine to leak a kernel pointer\nwith BPF_CMPXCHG. The PoC is basically probing for kernel addresses by storing the\nguessed address into the map slot as a scalar, and using the map value pointer as\nR0 while SRC_REG has a canary value to detect a matching address.\n\nFix it by checking R0 for pointers, and reject if that's the case for unprivileged\nprograms.",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "5ffa25502b5ab3d639829a2d1e316cff7f59a41e",
              "status": "affected",
              "versionType": "git",
              "lessThan": "f87a6c160ecc8c7b417d25f508d3f076fe346136"
            },
            {
              "version": "5ffa25502b5ab3d639829a2d1e316cff7f59a41e",
              "status": "affected",
              "versionType": "git",
              "lessThan": "a82fe085f344ef20b452cd5f481010ff96b5c4cd"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "5.12",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "5.12"
            },
            {
              "version": "5.15.11",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "version": "5.16",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}